How does Kino's father compare the gateway of death to the gateway of life so that Kino will have a better understanding?

Kino's father further explains that death is the great gateway, recalling how hard Kino thought it was to be born as he passed through the great gateway of life. Kino was afraid because he did not know anything about life, but he has been happy. Now, Kino is only afraid of death because he does not know anything about it.